Hot stamping is a metal forming process that may include heating an article or component to be formed and then stamping the article while it is still at an elevated temperature. For example, when hot stamping a steel article, the article may be heated to a temperature at which the microstructure of the steel is converted to austenite (e.g., austenitizing). This temperature may be around 900-950° C., depending on the composition of the steel.
In some hot stamping processes, the dies of the stamping mold that provide the desired shape to the stamped article may be cooled. The cooled dies may cool the article as it is being stamped. If the cooling rate of the dies is sufficiently high, the microstructure of the stamped article may be converted to a high strength phase. In the case of steel components, a sufficient cooling rate may result in a martensitic microstructure. Hot stamping may also be used to form articles made from other metals, such as aluminum. For example, aluminum alloys may be solution heat treated and quenched using a hot stamping process.
The dies for the hot stamping process may be cooled by cooling channels formed in the dies using mechanical processes such as gun drilling. Gun drilled cooling channels may reduce the ability to control cooling rates in various areas of the die and may limit the heat transfer surface area available for cooling in the die. These limitations may reduce the ability to impart microstructure variations in the hot stamped article.